Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries the full burden. It discloses that the operation is one-way, cannot be edited later, only voided, and that the invoice number comes from a gap-free sequence. This goes well beyond a simple 'issue invoice' statement, though it does not mention permissions or potential error cases.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is compact and front-loaded with the action, then adds consequential warnings. Every sentence earns its place, and the warnings about irreversibility and speculative use are clear without excess words.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given a single id parameter, no output schema, and no annotations, the description covers the most critical context: the irreversible finalization, the no-gap sequence constraint, and the need for user confirmation. It could clarify what a successful call returns or what state the invoice must be in, but the essential context is present.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0% and the description never explicitly explains what the 'id' parameter should reference (e.g., the invoice ID of a draft). It only says 'an invoice' indirectly, so an agent must infer that the id identifies the invoice to issue. The description does not compensate for the missing schema documentation.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('ISSUE an invoice') and elaborates on the action: allocate number, freeze contents, make it real. It distinguishes itself from siblings like invoices_create_draft and invoices_void by emphasizing the one-way, uneditable nature, so an agent can tell it apart without opening schemas.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives clear context on when not to use it (do not issue speculatively or to test) and instructs user confirmation for invoices not just created at the user's request. However, it does not explicitly name alternative tools (e.g., invoices_create_draft) or state the exact precondition that the invoice must be a draft, leaving some inference needed.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.